With the dramatic development of science and technology, mobile phones, digital cameras, tablet computers, laptop computers and the like portable electronic devices are becoming indispensable in people daily lives. Since these portable electronic devices are generally personally used and store some private data, the data and information stored therein, for example, address books, photos, personal information and the like are private. Once the electronic device is lost, such information and data would be taken used by others in an unauthorized manner, and some loss may be consequentially caused. At present, the electronic device is generally protected from being used in an unauthorized manner by setting password. However, the password is apt to be leaked or cracked, and thus the security is not ideal. Further, a user needs to remember the password and needs to enter the password correctly before using the electronic device, and if the user forgets the password, great inconvenience would be caused to the user. Therefore, fingerprint identification has been developed to achieve the objective of identity authentication, to improve the security of the personal data and information.
Capacitive fingerprint identification is a well-populated fingerprint identification mode, which judges the ridges and valleys of a user by sensing variations of the capacitance. However, the accuracy of the capacitive fingerprint identification is subject to a parasitic capacitor in a pixel sensing circuit. For example, to prevent a capacitance sensing layer from the interference from other circuits, in the related art, during circuit deployment, a metal layer is arranged under the capacitance sensing layer to achieve a shielding effect and thus prevent the circuits under the metal layer from causing interference to the capacitance sensing layer. However, a parasitic capacitor may be formed between the capacitance sensing layer and the metal layer, and the capacitance of the parasitic capacitor is generally greater than the capacitance of a contact capacitor generated by contact of the finger, which affects judgment of the capacitance of the contact capacitor by the pixel sensing circuit, and thus lowers the accuracy of fingerprint identification.
Further, noise detection has been widely applied to various identification systems to improve the identification accuracy. In the related art, with respect to the pixel sensing circuit for fingerprint identification, if noise at different frequencies need to be detected, clock pulse signals (which may also be referred to as clock signals) of the pixel sensing circuit needs to be modified. When different pixel sensing circuits detect the noise at different frequencies, the different pixel sensing circuits need to access different clock pulse signals, causing difficulty is practice of the circuit.